Currency testing means



Dec. 17, 1963 J, sTElNER 3,114,458

CURRENCY TESTING MEANS Filed June 30, 1960 2 Sheets-Sheet 1 A. 6'. SOURCE IN VEN TOR.

Jo/m 5 5/8/728! BY WM, W

FIG. 1

J. E. STEINER 3,114,458

CURRENCY TESTING MEANS Dec. 17, 1963 2 Sheets-Sheet 2 Filed June 50, 1960 r 42f m 3'3 & 'v vw INVENTOR.

JohnESfemer BY 64%, Q10 l/zw x/ fil United States Patent Ofiice 3,114,458 Patented Dec. 17, 1953 3,114,458 CURRENCY TESTING MEANS John E. Steiner, Rockford, 111., assignor, by mesne assignments, to Automatic Canteen Company of America, Chicago, Ill., a corporation of Delaware Filed June 30, 1961 Ser. No. 40,049 1 Claim. (Cl. 209-1115) This invention relates in general to a material evaluation arrangement and more particularly to a currency testing arrangement in which currency is automatically accepted, if legitimate, for coin change or other purpose and rejected if simulated or counterfeit.

In its organization, the present invention largely comprises novel circuit arrangements for a currency acceptance unit and constitutes an improvement of application Ser. No. 744,966, filed on June 27, 1958. That application and its forerunners disclose the mechanical structure and the basic circuit arrangements permitting certain currency evaluations to be made. The arrangement by which this is done comprises a therein into which currency such as a dollar bill is deposited. A door hingedly secured to the slide is closed over the deposited currency and the slide carrying the currency is reciprocated into a test position between certain lamps and light responsive cells. On the slide being operated into the test position, appropriate circuitry is controlled to operate a solenoid, which locks the slide in place. The lamps are then lighted. The light is transmitted in various degrees through respective areas of the currency depending, of course, on the color and value of the respective areas. The light responsive cells underlying the various areas respond to the quantity of light passing through those areas to provide an indication of the acceptability of the currency. Thus these cells are divided into three groups called black, white and green in accordance with the well known characteristics of currency notes. The currency is rejected it either the black or green cells receive more or less than a predetermined amount of light or if the white cells receive either more or less than a predetermined amount of light. If found unacceptable the slide is released and coin payout prevented. If found acceptable the currency is collected into a cash box on being stripped from the slide. This is done by a stripper motor, solenoid and guillotine arrangement which operate as described in the mentioned application. A coin payout motor is now energized and it operates a cam or finger in any well known manner to dispense the required coins. The slide is also released and automatically reciprocated into its unoperated position where it is prepared to receive another deposit of currency.

The present invention proposes an additional test which takes advantage of the known nouconductive condition and extremely high breakdown condition for currency when subjected to a high potential. This provides an additional tool for the determination of the presence of valid currency in the test area. Thus currency normally is nouconductive and, when damp, slightly conductive, but in any event has a breakdown characteristic substantially in excess of most other paper materials. By testing for this breakdown condition an additional determination can be made as to validity or invalidity of the tested material.

The breakdown condition is manifested by the radio frequency energy generated during breakdown. In this respect the invention is characterized by a very simple and novel circuit arrangement for detecting the presence of the RF. energy and amplifying the same to provide an indication of invalid currency.

It is one object of this invention to apply a high potential to a currency note, bill or paper for the purpose of determining the validity of said note, bill or paper.

horizontal slide having a trough It is another object of this invention to apply a high potential test to a currency note, bill or paper in conjunction with a light transmission test for the purpose of determining the validity of said note, bill or paper.

It is still another object of this invention to utilize the high frequency energy generated when a high potential is applied to an invalid currency note, bill or paper for the purpose of ascertaining the invalidity.

It is still another object of this invention to provide a material evaluation test comprising the application of a high potential to said material in combination with certain light transmission tests.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrangement and a combination of parts hereinafter fully described, illustrated in the accompanying drawing, and particularly pointed out in the appended claim, it being understood that various changes in the form, proportion, size and minor details of the structure and/or circuits, may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of this invention, there is illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, this invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated. The drawings comprising FIGS. 1 and 2 illustrate the circuit arrangement whereby the objectives of the present invention are accomplished, and it incorporates with some minor changes the principles disclosed in the aforementioned application.

Referring now to the drawings, there will be seen at the lower left of FIG. 1 a conventional source of A.C. power 35 connected across a 24 volt transformer 20 via conductors 30 and 32.

Transformer 20 furnishes power to the various test relays comprising the bad impulse relay 170, the black and white test relays 150 and 160 respectively and the tray clear test relay 140. In addition, the A.C. source 35 is connected to the constant voltage supply indicated by the box marked 34 for the purpose of ensuring a steady or constant voltage to the lights 117 and 119.

Lead 3%) is also connected to the common ring contacts 1431 and 102 carried by the rotor of a timer motor for selective interconnection with the various leads 40, 41, 42, 43, 44, 45 and 46 to permit the various tests, stripping and coin payout functions to be performed in the proper sequence. Also connected across the power supply 35 is the primary of transformer 6. With transformer 6 energized, the rectifier arrangement 12 connected across the secondary of the transformer 6 maintains a constant D.C. breaking voltage through contacts 111 on the payout motor 14 to positively prevent its operation until relay is operated.

The empty switch contacts 17 are normally closed if coins are available in the coin dispenser or disposal unit, as explained in the aforementioned application. If the unit is empty or coins are unavailable, switch 17 is open and 19 is closed. This extends lead 32 from the empty signal lamp 18 and switches 19 through contacts 21 to lead 30 for energizing the lamp. The lamp 18 on energizing lights to signal the empty condition.

The apparatus further comprises a series of switches M, 94 and 96, the latter two of which close if the note is properly positioned in the test area. Switch 92 closes 0 in response to the proper positioning of the slide in the test area.

As described in the aforementioned application, a lock solenoid 125 is provided for locking the slide in position when manually operated into the test area. A stripper motor 145 and stripper solenoid 135 are provided for operating the bill or note stripping arrangement including the guillotine described in the aforementioned application for removing the note from the test area on completion of a successful test.

White, green, and black cells 199a, 19% and 1199c respectively are provided beneath various areas of the bill in the test area and each has associated therewith an individually corresponding meter or galvanometer relay 70, 80 and 85, whose contacts are controlled responsive to the various tests.

A bad impulse relay 176 is operated in the event any validity test except the minimum light tests and the tray clear test are unsuccessful.

In the present arrangement relay 189 is provided to introduce positive booster battery 166 to the black cells 19%. This permits a determination to be made that at least the minimum amount of light is transmitted through the dark areas of the bill by operating the test relay 160. A similar test is also performed under the control of relay 180 for operating relay 160 under control of the white cells 199a and relay 7t).

A tray clear test is performed utilizing certain already described apparatus under control of the relay 196 which is operated responsive to the stripping of the bill from the test area. Relay 191) connects the black cells 1990 across the green relay 80 and the contacts 81 of the green relay $1) to the clear tray test relay 140.

The high potential detector for testing the validity of the note comprises a high voltage transformer 2G0 having a radio frequency choke 265 connected to its secondary. Choke coil 205 is in the neighborhood of 80 millihenries to provide a comparatively high impedance to radio frequency energy. The secondary of transformer 200 provides approximately 975 volts to the two 500K ohm series connected resistors 204, having condensers 206 in shunt therewith. This voltage is applied to electrode 201 which is placed in contact with one side of the note in the test area, While the note is grounded on its other side in any well known manner.

The detector also comprises a 12AV7, 210 and 220 which receive power through the transformer 290. Transformer 290 is connected directly across the power supply leads 30 and 32. Two secondaries on the transformer 2911 provide plate potential and filament power to the tubes. The potential is applied to the plate of tube 210 through resistor 218 and to the plate of tube 220 through the coil of relay 230.

The detector also includes the start relay 240 which initiates the test responsive to a signal from the timer motor 106 over lead 46, a detector bad impulse reset relay 250, bad bill alarm light 255 and a release relay 260.

Briefly described, the operation proceeds with the deposit of a currency note, bill or paper in the trough provided in the slide drawer and the manual operation of the slide to the currency testing position, as explained in the aforementioned application. The lock solenoid 125 is energized responsive to the closure of switches 92, 94 and 96.

If, for any reason such as the improper positioning of the bill or slide, contacts 92, 94 or 96 fail to close, solenoid 125 fails to operate. On release of the manual pressure on the slide, it is then reciprocated to its unoperated position due to the solenoid 125 failing to operate for locking it.

Operation of the lock solenoid 125 on the other hand completes a circuit to the start relay 120 and that relay initiates operation of the timer motor 100. The timer motor first completes a circuit to the lamps 117 and 119 via contact 101 to light the lamps.

With the slide drawer in its locked operated position, the currency note, bill or paper overlies light responsive cells 199a, 19% and 199a. As explained in the aforementioned application, these cells underlie respectively hued portions of the currency. Each has associated therewith a respective meter relay 70, 8t) and having respective contacts 71, 81 and 86.

The first test to be performed is an excess of light test. In the case of the white cells 199a, a potentiometer or adjustable resistor 198a in circuit with the white cells 199a and the associated relay 7%), limits the current therethrough to a predetermined value. It has been the previous practice to test for excess light passing through the black and green cells 19911 and 19% and the addition of this circuit arrangement permits the same function as can be performed with the white cells 199a. Thus if the current in cells 199a exceeds a predetermined amount as determined by the setting of resistor 193a, the relay contacts 71 close to place the bad impulse relay 170 across the secondary of transformer 20. Also in the event either cell groups 19% or 1990 respond to an excess of light passing through the currency, respective relays 8t) and 85 close contacts 81 and/or 86 respectively to place relay 1'70 across the secondary of transformer 20. With relay 170 across the transformer, it energizes to revent coin payout as will be explained.

Substantially, simultaneously with the energization of the flood lamps 117 and 119 and the light test just described, a high potential test is also performed. Normally, a currency note is nonconductive even in response to high potential. However, a good bill if humid or damp may conduct slightly. A counterfeit note will break down completely on the application of the high potential. This leads to the generation of considerable radio frequency energy and it is the detection of this energy that indicates a counterfeit bill. Thus the timer motor energizes relay 240 which energizes the high voltage transformer 200 to permit the discharge of R.F. energy across the note. Tubes 210 and 220 amplify the energy of the resultant discharge to operate relay 230. Relay 236 causes the energization of the bad impulse relay 1'70. If no RF. is detected, of course, the test proceeds normally.

Assuming that the tests just described were successful and relay 178 was not operated, the progress of timer motor causes contact 102 thereon to complete a circuit to relay 1S0. Relay now removes potentiometer 198a from the circuit of relay 7t and connects booster battery 166 for the black cell test to determine that sumcient light passes through the corresponding portions of the currency. It also connects the contacts 71 and 86 to the white and black test relays 160 and 150 respectively. Thus with the proper amount of light passing through the note, cells 199a and 1990 cause relays 70 and 85 respectively to close contacts 71 and 86 respectively. This places relays 160 and 150 respectively across the secondary of transformer 20 and each energizes to prepare for operation of the stripper motor 145 and the tray clear test.

The stripper motor 145 is operated by the timer motor 100 providing relays 159 and 169 are operated. It controls the stripper solenoid 135 and the guillotine, as explained in the aforementioned application, to strip the currency from the trough in the slide into the proper receptacle. Operation of relay is thereafter provided to permit performance of the tray clear test. Its operation, too, of course, is conditioned on the operation of relays 151i and 160 and the failure of the bad impulse relay 179 to operate. Relay 191) may be, of course, operated simultaneously with motor 145 and both may be under control of an intermediate relay, but the test controlled thereby is not performed until the tray is clear.

Relay 190 connects the black cells 199a across meter relay 3%) to provide cells and relay capable of reacting sufiiciently to the light. Contacts 81 of the green cell relay 80 are now connected to the tray clear test relay 14-1) and responsive to the closure of contacts 81, relay 140 is placed across the secondary of transformer 20 and operates. Of course, if the currency has not been cleared for any reason, insufficient light is transmitted and relay 80 does not energize sufficiently to close contacts 81. If relay 140 is therefore not operated by the time the reset relay 130 is operated, coin payout is prevented.

In detail the circuit operation proceeds in the following manner after the currency is inserted in the slide drawer and the slide placed into its operated position with the currency in the test area, as explained in the aforementioned application. The currency feeler switch contacts 94 and 96 close to indicate that the currency is properly positioned. Contacts 92 which are disposed in operative relationship to the slide in any well known manner, close responsive to the proper location of the slide in its operated position.

With the slide in its operated position, a circuit is completed from the A.C. supply 35 over conductor 32, through lock solenoid 125, through currency feeler contacts 96 and 94, tray feeler switch 92, contacts 131 on reset relay 130, the normally closed empty switch contacts 17, the coin jam contacts 21 and conductor 39 extending. to the other side of the AC. supply 35. The lock solenoid 125 energizes in this circuit to lock the slide carrying the currency in its operated position with the currency in the test area, as explained in the aforementioned application and closes contact 126.

Contacts 126 on closing connectthe conductor 30 extending through contacts 132 on reset relay 130, through the winding of start relay 120 to conductor 32 to energize relay 120.

Relay 120 on energizing closes contacts 121 in shunt with contacts 126 to complete a locking circuit for itself. It also closes contacts 122 to connect conductor 30 extending to the timer motor 106 This energizes the timer motor 100. Timer motor 100 now initiates operation of its rotor and the leading finger contact 1131 thereon extends power from conductor 30 to conductor 41 to light the scanning lamps 117 and 119. At contacts 123, it provides a holding circuit for solenoid 125.

With the lamps 117 and 119 lighted, the light is passed through the respective colored and light areas of the currency in the drawer, as explained in the aforementioned application. This light falling on the white, black and green cells 199a, 19917 and 1990 respectively causes corresponding current to pass through the cells. In the case of the cells 199a this current is extended through adjustable potentiometer 198a, contacts 185 and the winding of the associated meter relay 7. Current passing through cells 19% extends through contacts 195 and the winding of the associated meter relay 80. Current passing through cells 1990 extends over contacts 191 and 181 through the winding of the associated meter relay 85. If light in more than a predetermined quantity is passed through respective areas of the currency, the respective cells pass sufiicient current through the coils of the associated relays 71D, 80 and/or 85 to close the associated contacts 71, 81 and 86.

If for any reason such as an imperfect or counterfeit currency that passes too much light in one of the areas, closure of any of the contacts 71 or 86 connects one side of the secondary of transformer 20 extending through contacts 133 and conductor 134 to contacts 188 and/or contacts 183 to contacts 193 and the other side of the secondary of transformer 20 through the bad impulse relay 170. Contacts 81, if closed, connect conductor 134 to relay 170 through contacts 193. On being connected across the secondary of transformer 20, relay 170 operates. This prevents any coin disposal as will be explained.

Assuming that none of the aforementioned relays 70, 84) or 85 close their contacts, the next test will be conducted. As the rotor of motor 100 continues its operation, the contact 102 extends power from conductor 30 6 to conductor 40 through the first switch relay 1 and conductor 32 to energize switch relay 180.

This test is a determination that sufficient light passes the light and darkest areas of the bill to energize relays 169 and 150 respectively. At contacts 189' relay 180 locks operated through contacts 132. Relay 180 disconnects the contacts 86 and 71 from the bad impulse relay 170 at contacts 188 and 183 respectively. Instead at contacts 189 and 184 respectively it connects contacts 86 and 71 to relays 150 and 160 respectively. At contacts 185 the adjustable resistor or potentiometer 198 is disconnected from relay 7!) and cells 1990: connected directly to the winding of relay '70 at contacts 186. At contacts 187 positive potential from battery 166 is applied through adjustable resistor 167 and contacts 182 and 191 to permit relay 35 to close its contacts in response to a predetermined light value applied to cells 199c.

With the relay 70 connected directly across cells 199:: and the booster battery applied to relay and cells 199a both relays close their contacts 71 and 81 respectively responsive to the light passage. This connects the secondary of the 24 volt transformer through contacts 71 and 86 respectively, contacts 184- and 189 respectively to relays 160 and respectively. Both relays 159 and 161 therefore operate. If, on the other hand, contacts 71 or 86 fail to close indicating the failure or" the note to pass sufficient light through either the white or black area of the note, payout will be prevented due to the failure of relays 115%) and to operate as will be explained.

In the meantime the timer motor extends power on conductor 39 over lead 46 to relay 240. Relay 240 energizes to initiate the high potential test. it closes contacts 2 41 and completes a locking circuit for itself from conductor 32 through contacts 232 and 261. It also closes contact 242 to connect the primary of the high voltage transformer 2% across leads 36 and 32. At contacts 243 it prepares a circuit for relay 250. It will be recalled, of course, that electrode 201 is in contact with the currency and on generation of the high voltage created by energization of trans-former 206, that voltage appears between electrode 201 and ground. *If the note is valid no breakdown will occur, of course, and no rejection takes place.

If the note is valid but damp a certain amount of conduct-ion will occur from elect-rode 201 through the note, limited of course by the two 500K ohm resistors 204 in series therewith. In this situation the voltage at the grid of tube 210 is just slightly above ground as the potential across the radio frequency choke 2115 is comparatively low. The tube 210, therefore, does not conduct sufiiciently to create any reaction.

If the note were counterfeit or otherwise deficient, breakdown between electrode 201 and ground occurs with consequent arcing. This results in the generation of radio frequency energy to which the 80 millihenry choke 2115 presents considerable impedance.

The tube 21-4- responds by amplifying this signal and applying the same through the condenser 211 and the diode 212 to the grid of the second amplifier tube 220. It will be noted that the rectifier is poled to pass positive voltage to the grid of the tube, and on amplification thereof by tube 2220 relay 231 operates. This immediately opens the locking circuit for relay 241 at contacts 232 and connects lead 63 through the bad note light 255 and relay 250 to lead 299 extending to the secondary of transformer 24) through contacts 231.

Relay 240 now restores to de-energize the transformer 20%) and relay 230, while relay 250 energizes and lamp 255 lights to signal the condition. Relay 250 looks operated over contacts 251 before relay 236 restores. Relay 259 at contacts 251 also connects lead 63 from one side of transformer 20 through contacts 134 on reset relay 130 through contacts 252 to lead 297 extending through the bad impulse relay i to operate that relay.

In the event the note tested valid and relay 236 fails to operate, relay 240 remains locked up and its release is dependent on the subsequent operation of relay 260.

With the white test relay 160 operated, contacts 161 and 162 close and preparation is made for stripping the note and for coin payout.

Relay 160 also locks operated through contacts 163 and at contacts 161 it prepares for currency stripping and coin payout respectively.

Relay 150 locks operated at contacts 153 and closes contacts 151 and 152 to prepare for currency stripping and for coin payout.

With contacts 151 and 161 closed, a circuit is completed as soon as contact 1&2 on motor 100 extends power from conductor 30 to conductor 42 over contacts 172, contacts 161 and contacts 151 to energize the stripper motor 145.

Stripper motor 145 closes contacts 146 to extend the power on conductor 30 through the stripper solenoid 135, as explained in the aforementioned application, and the guillotine is operated as to strip the noted from the slide drawer. It will be understood, of course, that a relay may first be energized to control the operation of the motor 145, solenoid 135 and relay 190 through respective contacts. However, for the purpose of illustration, as explained in the aforementioned application, or at any desired time in the cycle, contacts 1 48 close when the bill or note is stripped. This extends the power on conductor 30 through relay 190 to initiate the tray clear test. Black cells are used in conjunction with the green relay 80 to determine that removal has occurred. In the meantime, stripping the note from the slide opens switches 94 and 96; however, solenoid 125 is held operated over contacts 123.

Relay 1% locks operated through contacts 197, 189 and 132. At contacts 194 it connects the winding of the green test meter relay 80 through potentiometer 85a to one side of the black cells 1990 and at contacts 192 connects the windings of relays 80 to the other side of the cells 19%. At contacts 196 it connects the contacts 51 of relay 80 to the tray clear test relay 140. If the tray is clear, the winding of relay 80 is energized suthciently to close contacts 81. This connects relay 1'40 across the secondary of transformer 20 to energize relay 140'. Relay 140 locks operated over contacts 142 and closes contacts 141 to prepare the payout sequence. Of course, if relay 140 does not operate, payout will not occur as will be explained.

In the mean-time, power extended over lead 42 by the rotor contact 102 is extended through relay 260 to energize that relay. It opens contacts 251 to restore relay 249, if not previously restored through operation of relays 230 and 250.

The motor contact 1112 coming in contact with conductor 43 after relay 14% is energized, extends power over contacts 173, 162, 152 and 141 to energize relay 110. Relay 110 operates to open contacts 111 and close contacts 112 and 113. Lights 117 and 119 extinguish when contact 101 disconnects from conductor 40.

Opening contacts 111 removes the D.C. breaking potential furnished by rectifier 12 in the output of transformer 6 and applied to the payout motor 14 to permit operation of the motor 14. The payout motor 14 now energizes over contacts 113.

As the payout motor operates it extends a control arm or finger 14' into the coin chute to dispense coins, as explained in the aforementioned application. With contacts 15 and 116 closed indicating successful coin disposal, relay 116 and the payout motor 14 lock operated through contacts 112, 16 and 15 until the payout cycle is completed. This prevents restoration of motor 14 and relay 110 when contact 102 leaves conductor 43. Y hen arm 4' returns to normal to open contacts 15 and 16, contacts 15 and 16 on opening, of course, open the holding circuits for relay 110 and motor 14 to restore them.

In the event a coin should jam to prevent the movement of the payout mechanism, contacts 15 and 16 remain open. The relay and motor are de-energized as soon as contact 102 leaves conductor 43. With contacts 21 thereafter failing to close, a later circuit is not completed to solenoid 125, and further tests are not conducted until the trouble is cleared.

As the rotor switch contact 101 comes in contact with conductor 45, power from conductor 30 is extended through contacts 123 to maintain the timer motor operated. A moment later, when contact 102 connects power to conductor 44 the reset relay 130 energizes. Thus relay 130 on energizing opens contacts 132 to open the circuit for start relay and that relay (lo-energizes. At contacts 133, relay restores operated relays 140, and 160. At contacts 131 the original operating circuit for solenoid 125 is opened. With relays 140, 150 and restored, the original circuit for payout motor 14 and relay 110 is restored. However, with switches 15 and 16 in their operated position, relay 110 and motor 14 continue operated, and on passing through the motor cycle and restoration of contacts 15 and 16, operation of the payout motor 14 and relay 110 is terminated. Relays and 190, of course, restore when their locking circuits are opened. Relay 120, on restoring, opens the holding circuit for solenoid 125 and it restores to release the slide which now returns to normal position.

Assuming normal operation, the rotor contact 101 and 102 pass from conductors 45 and 44 under control of motor 100. This terminates operation of the reset relay 130 and the timer motor 100 respectively and the apparatus is now prepared for another cycle. When the lock solenoid 125 is restored, the slide drawer is returned to its unoperated position, as explained in the aforementioned application. Switches 92, 94 and 96 therefore open.

In the event the bad impulse relay 170 was operated on any of the tests, circuits to stripper motor 145, and relays or relay 110 can not be completed as contacts 172 and 173 open. At contacts 171, relay 170 locks operated across contacts 133. Subsequent operation of the reset relay 130, of course, restores the locking circuit for relay 1'70 and it restores. Reset relay 130 at contacts 134 opens the circuit to relay 250 and lamp 255, if operated, to restore them.

In the event the relays 160 or 150 failed to operate responsive to the tests for sutficient light passage, the circuits to motor 145, solenoid 135, and relays 190 or 110 can not be completed as contacts 151, 152 or 161 and 162 remain open. Operation of the reset relay 130 thereafter releases the operated components as described.

If the tray clear test fails to operate relay 140, the circuit to relay 110 cannot be completed as contacts 141 remain open. The D.C. brake on the payout motor 14 is maintained and therefore coin payout cannot take place. Thereafter operation of the reset relay 130 restores the operated components as described.

In accordance with the above, there has been shown and described herein an improved material or currency evaluation arrangement for improving the operation, testing and control by such evaluation arrangement, but the particular embodiments or forms of the invention described herein are not limitations upon other manners of practicing the invention.

It will be understood that the concepts of this invention will have application also to the testing of other sheet material having an imprint, color or design on the surfaces thereof or embodied therein.

It will be further understood that other changes in the details of construction, arrangement and operation may be made without departing from the spirit of the invention, especially as defined in the following claim.

I claim:

A currency testing arrangement comprising in combination, an arrangement for exposing portions of a piece connected to said first and second means and adapted to accept said currency if the light values passing through currency corresponds to a predetermined light value and it no appreciable radio frequency energy is generated and means for controlling the time period in which said light values are determined and for controlling the time period in which said potential is applied.

References Cited in the file of this patent UNETED STATES PATENTS 2,280,119 German Apr. 21, 1942 2,320,516 Gammeter June 1, 1943 2,615,964 Hubertz Oct. 28, 1952 2,950,799 Timms Aug. 30, 1960 2,957,387 Patzer Oct. 25, 1960 3,019,397 Barber Feb. 6, 1962 

